Home Improvement Expert Danny Lipford

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How to Install Laminate Flooring on a Concrete Slab

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I’m installing a floating laminate floor on a concrete slab. Do I need to be concerned about moisture? -Gerald

Hi Gerald,

Excessive moisture is definitely a concern with laminate flooring on any subfloor, but particularly when installing it on a concrete slab. Before installing laminate flooring on a concrete slab, test the concrete first to be sure it’s dry enough:

  • A new concrete slab should have cured for a minimum of 30 days before installing any type of flooring, including laminate.
  • Before installing laminate flooring on a new or existing concrete slab, test the slab with a moisture meter to be sure it has no more than a 4.5% moisture reading.
  • Another (less accurate) way to test the moisture in a concrete slab is by taping an 18” x 18” piece of plastic to the concrete on all four sides, then allow the plastic to remain in place for 48 to 72 hours. If there is moisture under the plastic or it feels damp underneath, the slab has too high a moisture content to install a laminate floor.

If the concrete slab is dry enough to install laminate flooring:

  • Read and follow all instructions that came with your laminate flooring.
  • Fill in any low spots in the slab with floor patch compound and allow the compound to set.
  • Cover the concrete floor with a sheet of 6 mil plastic to act as a vapor barrier.
  • Lay foam sheeting on top of the plastic, if recommended by the maker of your laminate flooring.
  • Place the laminate flooring cartons in the room and allow the flooring to acclimate to the humidity in the room for 2-4 days before installing.
  • When installing the flooring, leave a 1/4” gap on all sides of the laminate floor to allow for expansion.

Good luck with your project,

Danny

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One Comment on “How to Install Laminate Flooring on a Concrete Slab”

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  1. david murphy Says:
    December 27th, 2011 at 6:49 pm

    concrete slab is in the livingroom and dinningroom in the dinning area at one side of the wall you can see that the slab floor has drop down from the molding 1/2 inch //some one told me that would get a contracter to drill holes and they pump concrete in the holes to rise the floor ????? why dont i just put some quick dry down my self

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